Tempest Picture Centering/Size

Samelak

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Just picked up a really nice Tempest cabaret, but the picture looks a bit small and definitely off centered to the left. I know virtually nothing about vectors. My experience is with rasters. How do I resize and center the picture. I don't see any knobs/dials on the chassis for it and I don't see a reference in the monitor manual.
 
Just picked up a really nice Tempest cabaret, but the picture looks a bit small and definitely off centered to the left. I know virtually nothing about vectors. My experience is with rasters. How do I resize and center the picture. I don't see any knobs/dials on the chassis for it and I don't see a reference in the monitor manual.

The adjustments are on the pcb.

I think you'll go into test mode via a switch in the coin door. Once you get to a grid pattern,the pcb pots will adjust the screen to your liking.
 
Yes, the pots are on the game board. There are 8 of them. Here's what they do:

X and Y each have SIZE, CENTER, and LIN (linearity). The size and center are self-explanatory, and can be adjusted on any of the test screens that have a box around the border. (Note you can cycle through the different test screens using the slam switch on the coin door, after entering test mode.) It's best to not have the X and Y size adjusted all the way to the edge of the screen, to save wear on the monitor. If you can back them off by an inch or so, that's usually good.

The LIN pots are adjusted using the crosshatch pattern (the last pattern using the slam switch). These basically adjust the X and Y width, but only around the edges of the screen, not the center. The trick with these is to look at the width of the boxes in the crosshatch, horizontally and vertically, and adjust the LIN pots, so the boxes are of consistent width all the way across the screen (i.e., make them the same size at the centers as they are at the edges.)

For the BIP (bipolar) pots, use the main test mode screen. The line above BONUS ADDER should read X111, as four evenly spaced letters. This is the best visual reference to use to adjust the BIP pots. Once you get that line of text straight (in addition to all of the above), the picture should look ok.

It may take a few iterations to get everything perfect, especially with the LIN and SIZE pots, as the LIN does change the size, so it actually may be best to start with them.

I only did a quick adjustment when I put the new board in there, so it wasn't perfect, but figured you were going to need to tweak it after moving (and you should know how to do it anyway, as the picture may drift over time.)

Also, the manual is in the binder that came with the cab. I'd recommend giving it a read, as there is lots of good info in there.

If you need any other help, let me know anytime.
 
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I must have gone through the manual 5 times and didn't see the reference to the pots on the PCBs. It's all adjusted now. Plays and looks great. I'm looking forward to getting the permanent board set.
 
This is a necro-thread, but now I'm curious (because I'm having to fine-tune my own board after accidentally nudging the pots): in which version of the Tempest manual are there recommendations on the 8 video pot settings? The one I have only says not to mess with them unless you are "a qualified technician."
 
This is a necro-thread, but now I'm curious (because I'm having to fine-tune my own board after accidentally nudging the pots): in which version of the Tempest manual are there recommendations on the 8 video pot settings? The one I have only says not to mess with them unless you are "a qualified technician."

I'm not aware that there is one. However the instructions above should be all you need.
 
Ah, okay, I misread the above as "RTFM." Will give it another tweak shortly.


Haha, no. I actually sold the OP the machine in question, and it came with printed manuals.

(So yes, I literally did say to read the manual, but not in that way, lol.) :)

The 6100 manual does contain info about adjusting convergence and purity, which I think is what I was referring to. But not adjusting the geometry.
 
Haha, no. I actually sold the OP the machine in question, and it came with printed manuals.

(So yes, I literally did say to read the manual, but not in that way, lol.) :)

The 6100 manual does contain info about adjusting convergence and purity, which I think is what I was referring to. But not adjusting the geometry.
Thanks. I picked up one of @komodo's boards as a spare, and tested it (monitor disconnected, natch) over the weekend. I didn't hit the 1-in-1000 that worked out of the box, but at least the X and Y OUT voltages look good, so there will be more to follow on that one sometime in the future.

But in the meantime, when I pulled my working original board, I obviously nudged some of the analog block pots, because the picture was compressed and generally crappy. "Okay no problem," I told myself. "You've done this before, just tweak them back to where they need to be."

An hour or so of tweaking later, I was almost back to normal... almost. There's a bit of weirdness that I haven't been able to fine-tune out. The most obvious is when a level is finished, there's a brief distortion in the middle of the tube as the C-shooter is progressing out into Hyperspace. I mocked up what it looks like on a Googled graphic, attached. The distortion is more-or-less what you see inside the inner circle. I also noticed that enemies will occasionally jitter while climbing up the tube, but this is very intermittent. The "level end" weirdness is consistent.

I tweaked the settings so many times trying to get rid of it I eventually lost all sense of what I had or hadn't tried yet and quit for a while. The checkerboard and crosshatch test screens all look like they should, at least to my (admittedly untrained) eye.
 

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Keep in mind that you can have other issues that can cause artifacts that can't be adjusted out. Things like bad DACs can cause BIP artifacts that can't be adjusted out, mathbox issues can cause digital artifacts that come and go, and you can even get marginal RAM that won't be caught by self-test, which can add glitches. I've seen all of the above.

Best thing to do is swap aux boards with a different good one, and make sure it's an issue on the main board, before you dig any deeper.
 
Welp, went down to try again, powered up, no video. Spot killer is on.

14839187.jpg

One day I will learn to not "fix" things. This, unfortunately, was not that day.
 
Unplug monitor, see if it plays blind.

Then boot into test mode (i.e., power up with test switch already flipped on). See if you hear sound from any button presses (which suggests test mode completed). If so, test XY voltage to be safe, then connect a monitor (or scope) and see what errors it's throwing.
 
Your game vectors are wonky too compared to mine. I don't have that "stair step" around the circle or the lines.
 
Unplug monitor, see if it plays blind.

Then boot into test mode (i.e., power up with test switch already flipped on). See if you hear sound from any button presses (which suggests test mode completed). If so, test XY voltage to be safe, then connect a monitor (or scope) and see what errors it's throwing.
Plays blind. No startup tones in test mode, buttons make the normal test mode sounds. That's as much as I've had a chance to check.

I suspect given the order of events that one or more of the 8 main board pots is loose or has failed. I'll pull it and do a close inspection over the weekend, and while I'm at it place an order for the recommended set of trimmer pots.
 
Measure the AC and DC voltages on XOUT and YOUT (with the monitor unplugged). If one is out of whack, that may tell you if one axis has a problem. (Which may be a pot, or anything else in the video section. But knowing which axis it is, is information.)

The pots are either broken or they aren't. And when they are, it's pretty easy to tell, just by visual inspection.
 
Measure the AC and DC voltages on XOUT and YOUT (with the monitor unplugged). If one is out of whack, that may tell you if one axis has a problem. (Which may be a pot, or anything else in the video section. But knowing which axis it is, is information.)

The pots are either broken or they aren't. And when they are, it's pretty easy to tell, just by visual inspection.
First thing I did yesterday. Voltages are fine, zero on DC and below 2V on AC in both axes.
 
First thing I did yesterday. Voltages are fine, zero on DC and below 2V on AC in both axes.

I thought that was before you lost the image. If it's playing blind, you want to test it again, as something has changed.

If the voltages are as you say, then you would have an image. So the fact that you don't have a picture (and spot killer is on) means something changed, and you probably don't have good XOUT/YOUT anymore.
 
I thought that was before you lost the image. If it's playing blind, you want to test it again, as something has changed.

If the voltages are as you say, then you would have an image. So the fact that you don't have a picture (and spot killer is on) means something changed, and you probably don't have good XOUT/YOUT anymore.
I can't remember the order now. I'll check them the next time I have a chance.
 
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